Alfredo Romero said his group’s lawyers also compiled evidence supporting opposition activists’ claims that National Guard troops had used excessive force against protesters, including shooting some point-blank with plastic shotgun pellets.

Romero said the beatings occurred at National Guard barracks No. 47 in the western city of Barquisimeto after at least 300 protesters were arrested across Venezuela for backing opposition candidate Henrique Capriles’ demand for a recount of all the votes cast Sunday.

Interrogators “put baseball caps on these kids’ head with a pro-government insignia … and made them say they recognized the Maduro government, and if they said ‘No’ they were beaten,” Romero said, adding that most of detainees ranged in age from 15 to 22.

The Associated Press sought comment from Interior Ministry spokesman Jorge Galindo but he did not answer his cellphone.

Romero called the crackdown Venezuela’s worst political persecution since 2006, when Chavez shut down the opposition TV station RCTV and more than 250 people were arrested. His 12-year-old group Foro Penal Venezolano has more than 200 lawyers who represent without charge people they consider political prisoners.

He said the group has complained to the Inter-American Human Rights Commission, whose rulings Venezuela’s government no longer recognizes, and is preparing a complaint to the International Criminal Court.

One of the worst cases of excessive force this week occurred in the central city of Valencia, members of the opposition’s youth wing said in Caracas. They said National Guardsmen fired plastic pellets at extremely close range at a group protesting the regime-friendly National Electoral Council’s decision to ratify the victory of Nicolas Maduro.

Maduro is to be sworn in Friday, and the government says 15 countries including Iran, China and Saudi Arabia were sending high-level delegations. Brazil said its president, Dilma Rousseff, was attending as was Argentina’s Cristina Fernandez, but it was not clear whether the president of neighboring Colombia, Juan Manuel Santos, would attend.

On Thursday, Maduro headed to Lima, Peru, for a meeting of presidents of the Union of South American Nations, UNASUR, to discuss Venezuela’s postelection tensions.

Capriles said in a Twitter message that he was evaluating whether to go, too.

The youth opposition wing members displayed photographs showing deep, bloody wounds on the skin of a man’s hand and arm. They said the man is Jonny Alvarado, a local leader of the centrist Proyecto Venezuela party who had been shot three times in the arm and was at risk of losing his hand. The AP confirmed Alvarado’s non-life-threatening injuries with the director of the hospital where he was treated.

In Monagas state, a group of 30 to 40 protesters was attacked by pro-government forces, then detained by authorities when they tried to flee, said Diego Scharifker, president of the youth wing of the Nuevo Tiempo party. One of the protesters remained jailed on charges of firing a gun even though tests didn’t find gunpowder residue on his hands, Scharifker said.

Romero said other activists described being arrested as they were walking home from peaceful protests.

The government alleges Capriles’ backers have incited all the postelection violence, which it says has caused eight deaths and 70 injuries. It also charges the opposition loyalists have burned eight health clinics and several offices of the ruling United Socialist Party of Venezuela.

Non-government media and private citizens have published photos of unmolested clinics and party offices that they said disproved the claims.

Chief Prosecutor Luisa Ortega reiterated on Thursday the government’s contention that neither it nor its supporters were to blame for any of the violence that followed Sunday’s vote.

“A common denominator is that the wounded and injured are all supporters of Chavismo,” she said in an interview on state TV.

Romero said 71 youths in all were arrested in Barquisimeto on Monday and Tuesday, when opposition supporters marched on regional offices of the electoral council, while 83 were arrested in Valencia over those two days.

He said it appeared all had been let go by Thursday, but many faced criminal charges that include public incitement, destroying public works and other crimes.

Other arrests occurred in the states of Barinas, Merida and Maracay, Romero added, but he said he didn’t have solid information on events there.

The prosecutor, Ortega, said Thursday that a total of 135 people had been arrested across Venezuela, with 90 of them charged with crimes.